import { Component } from 'react'

export default class App extends Component {
  constructor () {
    super()
    console.log('1. constructor执行')
  }
  componentDidMount () {
    console.log('3. componentDidMount执行')
  }
  render() {
    console.log('2. render执行')
    return <div>App组件</div>
  }
}